Extrusion tool, method for manufacturing shaped article with fins, and heat sink

ABSTRACT

An extrusion tool ( 10 ) according to the present invention includes a die main body ( 20 ) having a bearing hole ( 21 ) or defining an external configuration of the shaped article ( 1 ), the bearing hole ( 21 ) including a substrate forming portion ( 22 ) corresponding to the substrate ( 2 ) and fin forming portions ( 23 ) corresponding to the fins ( 3 ), and a plate member ( 30 ) to be disposed at an upstream side of the die main body ( 20 ). The plate member ( 30 ) is provided with a material passage ( 31 ) penetrating in the fore-and-aft direction and communicates with an upstream side opening of the bearing hole ( 21 ) of the die main body ( 20 ). The plate member ( 30 ) is provided with at least one vertical partitioning wall ( 33 ) ( 34 ) so as to cross the substrate forming portion ( 22 ) of the bearing hole ( 21 ) in the thickness direction of the substrate ( 2 ) in a state in which the plate member ( 30 ) is combined with the die main body ( 20 ), whereby the material passage ( 31 ) is divided into a plurality of small passages ( 31   a )( 31   b )( 31   c )( 31   d )( 31   e )( 31   f ). By using the extrusion tool for extruding a shaped article with fins such as a heat sink, excellent degree of flatness of the substrate can be obtained.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Priority is claimed to Japanese Patent Application No. 2001-386176, filed on Dec. 19, 2001 and U.S. Provisional Patent Application No. 60/352,597, filed on Jan. 31, 2002, the disclosure of which are incorporated by reference in their entireties.

[0002] This application is an application filed under 35 U.S.C. § 111(a) claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing date of Provisional Application No. 60/352,597 filed on Jan. 31, 2002 pursuant to 35 U.S.C. § 111(b).

TECHNICAL FIELD

[0003] The present invention relates to an extrusion tool for manufacturing a shaped article with a number of thin-plate type fins arranged on a substrate, a method for manufacturing the shaped article with fins by using the extrusion tool, and a heat sink manufactured by the method.

BACKGROUND ART

[0004] As one of heat releasing members used in electronic devices or the like, as shown in FIG. 6, an aluminum heat sink 1 having a number of thin plate-type fins 3 arranged like comb-teeth on one side of a substrate 2 can be exemplified. This heat sink 1 is used in such a manner that a heat generation element is attached to the other side 2 a of the substrate 2.

[0005] In the heat sink 1, the fins 3 are required to be large in tong ratio in order to enhance the heat releasing performance, and the other side of the substrate 2 is required to be flat so that a heat generation element can be attached in a closely fitted manner so as not to inhibit heat conduction from the heat generation element.

[0006] In many cases, as shown in FIG. 3, such a heat sink 1 is produced by an extrusion method using a die 50 having a bearing hole 21 corresponding to the circumferential configuration of the heat sink 1 because of the merit capable of manufacturing with fewer processes. The bearing hole 21 consists of a substrate forming portion 22 corresponding to the substrate 2 and fin forming portions 23 corresponding to the fins 3.

[0007] Furthermore, in general, when extruding a complex shaped article, uneven flow resistance of extruding material occurs depending on the bearing width of the die 50 and the distance from the bearing surface, which causes such a problem that the extruded article may have defects such as distortion, bending depending on the difference of material flow amount. One of the counter measures for such defects is to adjust the entire material flow amount balance by enlarging the bearing length at a portion with weaker flow resistance to thereby increase the flow resistance.

[0008] The aforementioned problem also occurs when extruding the heat sink 1, and therefore the flow balance is adjusted by changing the bearing length to obtain high tong ratio and high degree of flatness of the substrate 2. In details, in order to obtain fins 3 with high tong ratio, the bearing length of the substrate forming portion 22 which causes smaller flow resistance is so adjusted to be set longer than that of the fin forming portions 23. In addition, in order to obtain flatness of the substrate 2, the flow balance is adjusted by increasing the bearing length of the widthwise middle portion of the substrate forming portion 22 which causes smaller flow resistance than that of both end portions.

[0009] However, in setting up the bearing length to obtain flatness of the substrate 2, many trials must be repeated to individually cope with the matters since not only the size of the substrate 2 but also another factors such as the entire shape including the fins 3, extruding conditions and types of materials affect each other in a complex manner. Thus, the setting is time consuming and troublesome operations. Moreover, since a wider width W of the substrate 2 causes larger flow resistance difference between the end portions and the widthwise middle portion, deformation tends to occur and the degree of deformation is large. Therefore, the operations for setting the bearing length becomes complex.

[0010] Furthermore, in many cases, satisfactory degree of flatness is hard to be obtained in regard of a close contact with a heat generation element even when the bearing length of the substrate forming portion 22 is adjusted after troublesome operations. Therefore, the flatness is obtained by further conducting post-processing. In the post-processing, the extruded shaped article is subjected to roll straightening to obtain a roughly straightened article, and thereafter the fitting surface 2 a thereof to be attached to a heat generation element is ground. However, the higher the fins 3 get, the more difficult the operation of roll straightening becomes. Therefore, the aforementioned method is not a counter measure for achieving perfect flatness of the substrate 2. In other words, the aforementioned method is not a counter measure for assuredly manufacturing a heat sink having excellent heat releasing performance.

DISCLOSURE OF THE INVENTION

[0011] In view of the aforementioned technical background, the present invention aims to provide an extrusion tool capable of extruding a shaped article with fins such as a heat sink having a substrate with excellent flatness, a method for manufacturing a shaped article with fins using the extrusion tool, and a heat sink manufactured by the method.

[0012] For information, in this specification, the wording of “front” or “front end” denotes the outlet side of extruding material or the traveling direction of extruding material, whereas the wording of “rear” or “rear end” denotes the inlet side of extruding material or the direction opposite to the traveling direction of extruding material.

[0013] According to the first aspect of the present invention, an extrusion tool 10 for extruding a shaped article 1 with fins having a substrate 2 and a plurality of thin plate-type fins 3 arranged like comb-teeth on one side of the substrate 2, the extrusion tool 10, comprises:

[0014] a die main body 20 having a bearing hole 21 for defining an external configuration of the shaped article 1, the bearing hole 21 including a substrate forming portion 22 corresponding to the substrate 2 and fin forming portions 23 corresponding to the fins 3; and

[0015] a plate member 30 to be disposed at an upstream side of the die main body 20,

[0016] wherein the plate member 30 is provided with a material passage 31 penetrating in the fore-and-aft direction and communicates with an upstream side opening of the bearing hole 21 of the die main body 20, and

[0017] wherein the plate member 30 is provided with at least one vertical partitioning wall 33, 34 so as to cross the substrate forming portion 22 of the bearing hole 21 in the thickness direction of the substrate 2 in a state in which the plate member 30 is combined with the die main body 20, whereby the material passage 31 is divided into a plurality of small passages 31 a, 31 b, 31 c, 31 d, 31 e and 31 f.

[0018] It is preferable that two or more vertical partitioning walls 33, 34 are provided in the material passage 31 of the plate member 30.

[0019] It is preferable that a merging space 37 a, 37 b communicating with the plurality of small passages 31 a, 31 b, 31 c, 31 d, 31 e, 31 f is provided at a downstream side of the material passage 31 of the plate member 30.

[0020] It is preferable that the vertical partitioning wall 33, 34 is formed so as to cross the fin forming portions 23.

[0021] It is preferable that the extrusion tool further comprises a horizontal partitioning wall 32 formed in the material passage 31 of the plate member 30, wherein the horizontal partitioning wall 32 is positioned at a boundary portion between the substrate forming portion 22 and the fin forming portions 23 in a state in which the plate member 30 is combined with the die main body 20.

[0022] It is preferable that the horizontal partitioning wall 32 is formed to have an inclined surface 35 at a front portion facing the substrate forming portion 22, the inclined surface 35 being inclined toward the fin forming portions 23.

[0023] It is preferable that the die main body 20 is provided with a dented portion 24 formed at an upstream side thereof and communicated with the bearing hole 21 for introducing the extruding material into the bearing hole 21.

[0024] According to the second aspect of the present invention, a method for manufacturing a shaped article with a plurality of thin plate-type fins 3 arranged like comb-teeth on one side of a substrate 2, comprises:

[0025] preparing an extrusion tool 10 comprising a die main body 20 having a bearing hole 21 for defining an external configuration of the shaped article 1, the bearing hole 21 including a substrate forming portion 22 corresponding to the substrate 2 and fin forming portions 23 corresponding to the fins 3, and a plate member 30 to be disposed at an upstream side of the die main body 20, wherein the plate member 30 is provided with a material passage 31 penetrating in the fore-and-aft direction and communicated with an upstream side opening of the bearing hole 21 of the die main body 20, and wherein the plate member 30 is provided with at least one vertical partitioning wall 33, 34 so as to cross the substrate forming portion 22 of the bearing hole 21 in the thickness direction of the substrate 2 in a state in which the plate member 30 is combined with the die main body 20, whereby the material passage 31 is divided into a plurality of small passages 31 a, 31 b, 31 c, 31 d, 31 e, 31 f;

[0026] extruding an extruding material using the extrusion tool 10 such-that-the extruding material divided into the small passages 31 a, 31 b, 31 c, 31 d, 31 e, 31 f of the pale member 30 are merged to be pressed and adhered and then extruded through the bearing hole 21.

[0027] It is preferable that the extruding material is aluminum.

[0028] It is preferable that the shaped article with a plurality of thin plate-type fins is a heat sink.

[0029] According to the third aspect of the present invention, a heat sink manufactured by the method mentioned above.

[0030] With the extrusion tool according to the present invention, since the flow resistance is uniformalized in the widthwise direction of the substrate forming portion of the bearing hole, the accurate bearing hole size can be obtained. Therefore, a substrate with high degree of flatness can be obtained.

[0031] In cases where two or more vertical partitioning walls are provided in the extrusion tool, the flow resistance can be further uniformalized, thereby causing a substrate with excellent degree of flatness.

[0032] Furthermore, in cases where a merging space communicating with the small passages is provided at the downstream side of the material passage of the plate member, the merging of extruding material can be conducted in the plate member.

[0033] Furthermore, in cases where the vertical partitioning wall is provided so as to cross the fin forming portions, flow resistance difference can be decreased.

[0034] In cases where the horizontal partitioning wall is formed in the material passage of the plate member so as to position at a boundary portion between the substrate forming portion and the fin forming portions in a state in which the plate member is combined with the die main body, the flow rate in the fin forming portions can be adjusted and therefore fins with high tong ratio can be preferably formed.

[0035] It is preferable that the horizontal partitioning wall is formed to have an inclined surface inclined toward the fin forming portions. This can increase the flow amount toward the substrate forming portion.

[0036] It is preferable that the dented portion communicated with the bearing hole for introducing the extruding material to the bearing hole is formed at the upstream portion of the die main body. In this case, the merging of extruding material can be performed in the die main body.

[0037] According to the method for manufacturing a shaped article with fins of the present invention, the extruding material divided into and supplied through the small passages in the plate member are merged to be pressed and adhered, and then extruded through the bearing hole. Therefore, the flow resistance in the widthwise direction of the substrate forming portion of the bearing hole can be uniformalized. Accordingly, an accurate size of the bearing hole can be obtained, resulting in a substrate with high degree of flatness, which in turn enables to obtain a predetermined degree of flatness without post-processing.

[0038] The method for manufacturing the shaped article with fins can be preferably applied when aluminum is used as extruding material.

[0039] In addition, it is preferable that the shaped article with fins is a heat sink. A heat sink which has excellent heat releasing performance and can closely fit to a heat generation element can be produced due to the excellent degree of flatness of the substrate. Furthermore, since post-processing for obtaining flatness is not required, an excellent heat sink can be manufactured with easy process.

[0040] Since the heat sink according to the present invention is produced as mentioned above, the heat sink can closely fit to a heat generation element, resulting in excellent heat releasing performance.

BRIEF DESCRIPTION OF DRAWING

[0041]FIG. 1 is a rear view showing an embodiment of an extrusion tool according to the present invention viewed from the rear end of a plate member constituting the extrusion tool.

[0042]FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 showing the extrusion process of a heat sink using the extrusion tool shown in FIG. 1.

[0043]FIG. 3 is a perspective view showing a die main body viewed from the rear upper side thereof.

[0044]FIG. 4 is a perspective view showing the plate member viewed from the front upper side thereof.

[0045]FIG. 5 is a cross-sectional view taken along the line V-V of FIG. 1 showing the extrusion process of the heat sink using the extrusion tool shown in FIG. 1.

[0046]FIG. 6 is a perspective view showing the heat sink to be manufactured by the extrusion tool shown in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0047] FIGS. 1 to 5 show one embodiment of an extrusion tool 10 according to the present invention which is used to extrude an aluminum heat sink 1 in which a number of thin plate-type fins 3 are arranged like comb-teeth on one side of a thick substrate 2 as shown in FIG. 6. In FIGS. 2 and 5, the reference numeral “40” denotes a container and “41” denotes extruding material loaded in this container 40.

[0048] The extrusion tool 10 includes a die main body 20 and a plate member 30 combined with the die main body 20

[0049] As shown in FIGS. 1-3 and 5, the die main body 20 has a bearing hole 21 for defining the external periphery of the heat sink 1. The bearing hole 21 consists of a substrate forming portion 22 corresponding to the substrate 2 and fin forming portions 23 corresponding to the fins 3. Formed behind the bearing hole 21 is a dented portion 24 for introducing extruding material to the bearing hole 21.

[0050] As shown in FIGS. 1, 2, 4 and 5, the plate member 30 has a material passage 31 which penetrates in the fore-and-aft direction and guides the extruding material to the rear end opening of the dented portion 24 of the die main body 20. The material passage 31 is divided into six individual small-passages 31 a, 31 b, 31 c, 31 d, 31 e and 31 f by a horizontal partitioning wall 32 disposed at the vertically bisected position and two vertical partitioning walls 33 and 34 disposed at the horizontally trisected positions.

[0051] In a state in which the plate member 30 is combined with the die main body 20, as shown in FIGS. 1 and 2, the horizontal partitioning wall 32 is positioned approximately at the boundary portion between the substrate forming portion 22 and the fin forming portions 23 of the die main body 20 with the inclined surface 35 formed at the tip end portion thereof inclined toward the fin forming portions 23, while its tip surface 36 thereof is positioned in the same plane as the front end surface of the plate member 30. The horizontal partitioning wall 32 divides the extruding material 41 into the upper small passages 31 a, 31 b and 31 c and the lower small passage 31 d, 31 e and 31 f before introducing the extruding material into the die main body 20. When the extruding material is introduced into the die main body 20, the inclined surface 35 of the horizontal partitioning wall 32 increases the flow amount of the extruding material toward the plate forming portion 22 because of the enlarged cross-sectional area of the lower passages 31 d, 31 e and 31 f.

[0052] In the state in which the plate member 30 is combined with the die main body 20, the aforementioned vertical partitioning walls 33 and 34 are disposed perpendicular to the substrate forming portion 22 and the fin- forming portions 23 at the positions where the bearing hole 21 is trisected in the widthwise W direction of the substrate 2. These vertical partitioning walls 33 and 34 are located behind the front end surface of the plate member 30. At the front end side of the material passage 31, the upper three small passages 31 a, 31 b and 31 c are communicated with each other to thereby form an upper merging space 37 a. Similarly, the lower three small passages 31 d, 31 e and 31 f are communicated with each other to thereby form a lower merging space 37 b. The vertical partitioning walls 33 and 34 divide the extruding material 41 into the left upper and lower small passages 31 a and 31 d, the central upper and lower small passages 31 b and 31 e and the right upper and lower small passages 31 c and 31 f. The extruding material 41 passing through these upper (lower) small passages 31 a, 31 b and 31 c (31 d, 31 e and 31 f) and divided into three flows in the horizontal direction merges in the merging space 37 a (37 b) to be pressed and integrally adhered (see FIG. 5)

[0053] Therefore, in the extrusion tool 10 in a state in which the die main body 20 and the plate member 30 are combined, extruding material flows and the heat sink 1 is formed as follows.

[0054] The extruding material 41 in the container 40 is divided into and passes through six individual small passages 31 a, 31 b, 31 c, 31 d, 31 e and 31 f of the plate member 30, and the extruding material 41 passes through the upper small passages 31 a, 31 b and 31 c and then merges to be pressed and integrally adhered with each other in the upper merging space 37 a, while the extruding material 41 passed through the lower small passages 31 d, 31 e and 31 f merges to be pressed and integrally adhered in the lower merging space 37 b. That is, the extruding material 41 divided into six in the horizontal and vertical directions at the downstream side end portion of the plate member 30 are joined at the upper and lower merging spaces, respectively, to cause two flows, i.e., the upper flow and the lower flow. Thereafter, these two flows are merged to be pressed and integrally adhered in the dented portion 24 of the die main body 20. Thus, the extruding material 41 is integrally extruded through the bearing hole 21, forming the heat sink 1 of the predetermined configuration.

[0055] When the extruding material passes through the passage 31 of the plate member 30, a relatively large flow resistance occurs at portions near lateral ends of the passage 31 and near the vertical partitioning walls 33 and 34. On the other hand, a relatively small flow resistance occurs at portions away them. Thus, the flow resistance differs along the transversal direction of the passage. This difference in flow resistance gradually decreases as the extruding material passing through the laterally arranged three small passages 31 a, 31 b and 31 c merges in the merging space 37 a(37 b) and then the extruding material passing through the upper merging space 37 a and the lower merging space 37 b merges in the dented portion 24 of the die main body 20. Then, the merged extruding material is introduced into the bearing hole 21 in a state in which the flow balance is substantially uniformalized. As a result, the flow resistance in the widthwise direction of the substrate forming portion 22 in the bearing hole 21 is uniformalized, and extrusion can be conducted with size of a bearing hole accurately reflected, and therefore the substrate 2 having high degree of flatness can be formed.

[0056] In the plate member 30 according to this embodiment of the present invention, in addition to the aforementioned vertical partitioning walls 33, 34, the horizontal partitioning wall 32 is formed. This horizontal partitioning wall 32 contributes to the forming of fins with high tong ratio since it causes an increased flow resistance in the fin forming portions 23 by dividing the extruding material 41 into the upper and lower flows. In addition to the substrate 2 with flatness formed by the aforementioned vertical partitioning walls 33 and 34, by the horizontal partitioning wall 32, fins 3 with high tong ratio can be formed. This makes it possible to extrude a heat sink with excellent heat releasing performance.

[0057] An extrusion tool according to the present invention, however, is not limited to the aforementioned embodiment.

[0058] At least one vertical partitioning wall of the plate member 30 can decrease the difference in flow resistance in the widthwise direction of the substrate forming portion 22. It is preferable that two or more vertical partitioning walls 33 and 34 of the plate member 30 are provided. The appropriate number of vertical partitioning walls 33 and 34 varies depending on the width W of the substrate 2. The wider the width W is, the more the number of vertical partitioning walls 33 and 34 becomes. However, too many vertical partitioning walls 33 and 34 may cause inconvenience such as too large flow resistance as a whole and/or deterioration of strength of partitioning walls due to the narrowed width thereof. For example, the number of vertical partitioning wall is preferably two or three when the width W of the substrate 2 is about 300 mm.

[0059] Furthermore, in the aforementioned embodiment, although the vertical partitioning walls 33 and 34 are provided so as to cross the substrate forming portion 22 of the bearing hole 21 and the fin forming portions 23, these walls may be provided so as to cross at least the substrate forming portion 22. However, it is preferable that these walls are disposed so as to cross the substrate forming portion 22 and the fin forming portions 23 so as to decrease the flow resistance difference.

[0060] Furthermore, in the aforementioned extrusion tool 10, although the merging of extruding material 41 divided in the horizontal direction is conducted in the upper and lower merging spaces of the plate member 30 and the merging of extruding materials 41 divided in the vertical direction is conducted in the dented portion 24 of the die main body 20, the positions for merging the extruding material are not limited to the above. For example, the merging of extruding material in the vertical direction may be conducted in the plate member 30, and a die main body having a bearing hole formed at the rear surface thereof may be combined with the plate member. Alternatively, an additional plate member having an extruding material merging space may be disposed between the die main body 20 and the plate member 30.

[0061] Furthermore, in the extrusion tool according to the present invention, the shape of the substrate forming portion 22 of the die main body 20, or the shape of the substrate of an extruded article with fins, is not limited to the aforementioned flat-plate shape. For example, in the present invention, the substrate forming portion, or the substrate of the extruded article, may have legs or the like for attaching it to a heat generation element.

[0062] According to the method for producing a shaped article with fins, the extrusion tool 10 is used, and extruding material supplied in a divided manner through small passages 31 a, 31 b, 31 c, 31 d, 31 e and 31 f of the plate member 30 are merged and then extruded through the bearing hole 21. Therefore, the flow resistance in the widthwise direction of the substrate forming portion 22 can be uniformalized, which enables the manufacturing of a shaped article having fins with excellent degree of flatness of the substrate 2. Accordingly, a predetermined shaped article with fins can be manufactured without conducting post-processing such as roll straightening and/or grinding.

[0063] Such a shaped article with fins can be preferably manufactured when the extruding material is aluminum. The kind of aluminum is not limited to a specific one and can be widely selected among high purity aluminum, JIS A1000 series aluminum or its alloy, Al—Cu based alloy of JIS A2000 series, Al—Mn based alloy of JIS A3000 series, Al—Si based alloy of JIS A4000 series, Al—Mg based alloy of JIS A5000 series, Al—Si—Mg based alloy of JIS A6000 series, Al—Zn—Mg—Cu or Al—Zn—Mg based alloy of JIS A7000 series and the like.

[0064] Furthermore, the aforementioned manufacturing method is suitably used for producing a heat sink and is capable of obtaining a substrate with excellent degree of flatness. Therefore, a heat sink with a good contact with various types of heat generation elements can be produced by extrusion only. As heat sink material, JIS A 6000 aluminum alloy with good extrusion and heat conduction, particularly JIS A6063 aluminum alloy, can be recommended.

EXAMPLES

[0065] Experiments on extrusion were conducted using an extrusion tool 1 shown in FIGS. 1 to 5 and several types of extrusion tools in which the number of vertical partitioning walls in the plate member 30 was changed.

[0066] In the heat sink 1, a width W of the substrate 2 was set to be 299.8 mm, the thickness T of the substrate 2 was set to be 6.5 mm, the thickness FT of the fin 3 was set to be 1.5 mm, the height FH of the fin 3 was set to be 15.5 mm, and the fin pitch FP was set to be 4.2 mm.

[0067] In the extrusion tool 10, the die main body 20 was formed to have a bearing hole 21 having a size corresponding to the size of the substrate forming portion 22 and the fin forming portions 23 of the aforementioned heat sink 1. The depth of the dented portion 24 was set to be 10 mm.

[0068] Plate members 30 having a common horizontal partitioning wall 32 and four different number of vertical partitioning walls as shown below were prepared and combined with the die main body 20. In the horizontal partitioning wall 32, the thickness S1 was set to be 26 mm, the width S2 of the tip end surface 36 was set to be 4 mm, and the inclination angle θ of the inclined surface 35 was set to be 45° (see FIG. 2). Furthermore, in the vertical partitioning walls, regardless of its number, the thickness S3 was set to be 20 mm and the depth S4 of the merging space 37 a (37 b) was set to be 40 mm while the thickness S5 of the plate member 30 was set to be 130 mm (see FIG. 5).

Example 1

[0069] One vertical partitioning wall was formed at the widthwise central position of the material passage 31, i.e., at the center of the substrate forming portion 22, in a state in which the plate member is combined with the die main body 10. Therefore, the material passage 31 was divided into four by one vertical partitioning wall and one horizontal partitioning wall.

Example 2

[0070] Two vertical partitioning walls were formed at the positions where the material passage 31 was trisected in the horizontal direction, i.e., at the positions shown in FIG. 4. Therefore, the material passage 31 was divided into six by two vertical partitioning walls and one horizontal partitioning wall.

Example 3

[0071] Three vertical partitioning walls were formed at the positions where the material passage 31 was quadrisected in the horizontal direction. Therefore, the material passage 31 was divided into eight by three vertical partitioning walls and one horizontal partitioning wall.

Comparative Example

[0072] No vertical partition was formed. Therefore, the material passage 31 was divided into two by only one horizontal partitioning wall.

[0073] Using the aforementioned four types of extrusion tools, ten elongated shaped articles with length of 3100 mm were extruded by using JIS A6063 aluminum alloy as extruding material, respectively.

[0074] In each of obtained ten elongated shaped articles, the degree of flatness of the substrate was measured. The degree of flatness is represented by the difference between the highest position and the lowest position in the fitting surface 2 a to the heat generation element or the like. The minimum value (which means the most excellent degree of flatness) to the maximum value in each degree of flatness of ten elongated shaped articles is shown in Table 1. TABLE 1 Comparative Example 1 Example 2 Example 3 Example Number of 1 2 3 None vertical petit- ioning wall Degree of 1.2-1.5 0.5-1.0 0.3-0.8 2.0-3.0 flatness (mm)

[0075] From the results shown in Table 1, it was confirmed that the degree of flatness of the substrate can be improved by providing at least one vertical partitioning wall in the material passage of the plate member.

[0076] Furthermore, in the heat sinks manufactured by using the extrusion tools of Examples 1 to 3, the degree of flatness of the substrate were in a satisfactory level in regard of close contact with the heat generation element. In addition, there was no deformation in fins and they were extruded in a satisfactory manner.

[0077] While illustrative embodiments of the present invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, but includes any and all embodiments having modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based the language employed in the claims and riot limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term “preferably” is non-exclusive and means “preferably, but not limited to.” Means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not recited.

INDUSTRIAL APPLICABILITY

[0078] According to the extrusion tool of the present invention, since the material flow resistance in the widthwise direction of the substrate forming portion of the bearing hole can be uniformalized, the substrate with excellent degree of flatness can be formed. Furthermore, since the flow resistance in the fin forming portions increases as compared to that in the substrate forming portion, fins with high tong ratio can be formed. Thus, it is suitably used for manufacturing a heat sink in which a substrate can closely contact with a heat generation element, and a heat sink with excellent heat releasing performance can be obtained. 

1. An extrusion tool for extruding a shaped article with fins having a substrate and a plurality of thin plate-type fins arranged like comb-teeth on one side of the substrate, said extrusion tool comprising: a die main body having a bearing hole for defining an external configuration of the shaped article, said bearing hole including a substrate forming portion corresponding to the substrate and fin forming portions corresponding to the fins; and a plate member to be disposed at a downstream side of said die main body, wherein said plate member is provided with a material passage penetrating in the fore-and-aft direction and that communicates with an upstream side opening of said bearing hole of said die main body, and wherein said plate member is provided with at least one vertical partitioning wall so as to cross said substrate forming portion of said bearing hole in the thickness direction of the substrate in a state in which said plate member is combined with said die main body, whereby the material passage is divided into a plurality of small passages.
 2. The extrusion tool as recited in claim 1, wherein two or more vertical partitioning walls are provided in said material passage of said plate member.
 3. The extrusion tool as recited in claim 1, wherein a merging space communicating said plurality of small passages is provided at a downstream side portion of said material passage of said plate member.
 4. The extrusion tool as recited in claim 1, wherein said vertical partitioning wall is formed so as to cross said fin forming portions.
 5. The extrusion tool as recited in claim 1, further comprising a horizontal partitioning wall formed in said material passage of said plate member, wherein said horizontal partitioning wall is positioned at a boundary portion between said substrate forming portion and said fin forming portions in a state in which said plate member is combined with said die main body.
 6. The extrusion tool as recited in claim 1, wherein said horizontal partitioning wall is formed to have an inclined surface at a front portion facing said substrate forming portion, said inclined surface being inclined toward said fin forming portions.
 7. The extrusion tool as recited in claim 1, wherein said die main body is provided with a dented portion formed at an upstream side portion thereof and communicated with said bearing hole for introducing the extruding material into said bearing hole.
 8. A method for manufacturing a shaped article with a plurality of thin plate-type fins arranged like comb-teeth on one side of a substrate, said method comprising: preparing an extrusion tool comprising a die main body having a bearing hole for defining an external configuration of said shaped article, said bearing hole including a substrate forming portion corresponding to the substrate and fin forming portions corresponding to the fins, and a plate member to be disposed at an upstream side of said die main body, wherein said plate member is provided with a material passage penetrating in the fore-and-aft direction and that communicates with an upstream side opening of said bearing hole of said die main body, and wherein said plate member is provided with at least one vertical partitioning wall so as to cross said substrate forming portion of said bearing hole in the thickness direction of the substrate in a state in which said plate member is combined with said die main body, whereby the material passage is divided into a plurality of small passages; extruding an extruding material using said extrusion tool such that the extruding material divided by said small passages of said plate member are merged to be pressed and adhered and then extruded through said bearing hole.
 9. The method for manufacturing a shaped article with fins as set recited in claim 8, wherein the extruding material is aluminum.
 10. The method for manufacturing a shaped article with fins as set recited in claim 8, wherein the shaped article with a plurality of thin plate-type fins is a heat sink.
 11. heat sink manufactured by the method as recited in claim
 10. 